1. Field of the Invention
This invention generally relates to a method of individually inserting terminals connected in a strip into printed circuit boards (or similar substrate) for the electronics industry, and the apparatus for carrying out the method.
2. Background of the Invention
The purpose of terminal insertion equipment is to index continuous strip terminals packaged on reels and individually shear the terminals from their integral carrier strip and insert them into a printed circuit board (PCB) or other substrate. Presently, semi-automatic insertion equipment for the electronics industry share some common features. For example, terminals are commonly fed through a stationary feedtrack by an air cylinder driven feedfinger. Terminals are removed from their integral carrier strips by horizontal shear motion across the carrier strip material thickness. The sheared terminal subsequently is vertically inserted into a printed circuit board with a pneumatically driven plunger. The proper location of the printed circuit board is achieved through the aid of locating pins and anvils protruding upward from the flat surface of a lower tooling module. Typically, the printed circuit board is stationary during the insertion cycle.
Numerous insertion machines have been devised for inserting terminal pins and other components into apertures of printed circuit boards and other substrates. When the terminal pins are connected in a strip, the insertion equipment must first sever the pins from the strip prior to insertion. Frequently, this entails a separate shearing step. However, the provision of separate cutting elements increases the number of moving components of the machine, rendering the machine more expensive and susceptible to breakdown.
While some insertion equipment is very sophisticated and can fully automatically insert, by means of computer control, numerous terminals into printed circuit boards, such fully automated machines are very expensive and are not always required for simple applications.
In U.S. Pat. No. 4,598,471 to Elsbree, Jr. et al., a pin inserter for electronic boards is disclosed wherein a mechanism is provided for rotating the connecting webbing in order to twist the webbing and break the pins off the carrier strip. Not only does this arrangement suffer the disadvantages of cost and reliability aforementioned, but the pins themselves may be damaged or bent and the carrier strip is not severed along a clean sharp edge.
In U.S. Pat. No. 4,543,714 to Seffernick et al., an insertion machine is described for inserting circuit module terminals. A carrier web is periodically advanced in stepwise manner. While the substrate follows a path of advancement, a separation apparatus is used which subjects the terminals to a blast of compressed air which propels the separated terminals toward the substrate. This apparatus, in addition to its inherent complexity, can only be used for limited applications.